From the Auerbach article above on how they came about scheduling.
Competitive balance
There is a hierarchy of the 18-team Big Ten football conference consisting of historic powers like Ohio State, Michigan, Penn State and USC, annual competitive programs like Washington, Oregon, Wisconsin and Iowa plus others such as UCLA, Michigan State and Northwestern which routinely have competed for league titles.
In order to provide balanced scheduling, a scheduling matrix was developed. It first included two tiers of nine teams, then three tiers of six teams and finally six tiers of three teams.
“Our goal was to try and create those opportunities where we eliminated the outliers,” Kenny said. “So the hardest schedule and the easiest schedule on paper should all be around a consistent equator line as you look across all 18.”
The 262nd schedule was the only one in which all 18 teams had four or five games against each of the nine-team tiers established.